Method for constructing reliable flash memory storage system in cooperative usage of erasure codes and error correction codes

Abstract

The present invention discloses a method for constructing reliable flash memory storage system in cooperative usage of erasure codes and error correction codes, comprising the following steps: receiving an IO request R, determining whether the IO request R is a write request or a read request; for a write request, applying erasure codes to s numbers of user data pages of each stripping so as to generate a total s+k numbers of pages to be written, writing the s+k numbers of pages to be written together with verification and error correction codes of each page to a storage device; for a read request, dividing the read request into sub-requests which belong to different strippings, and for each sub-request, reading out each page and the verification and error correction codes of each page, calculating the verification of each page and identifying bit errors and finding out the page with the largest number of errors, wherein if the number of errors of the page is not greater than the largest error bit T that can be corrected by the error correction codes to be adopted, the error correction codes will be adopted in correcting bit errors in the sub-requests, otherwise the erasure codes will be adopted to correct bit errors in the sub-requests, and the data requested by the sub-requests will be sent back. The method herein has the advantages of low calculating overhead, fast IO speed, and marked effect of prolonged flash memory lifespan.

Description

technical field [0001] The invention relates to the field of computer storage systems, in particular to a construction method of a reliable flash memory storage system using erasure correction codes and error correction codes in cooperation. Background technique [0002] Flash memory is widely deployed in large-scale storage systems because of its superior performance. However, its limited lifespan hinders the promotion of flash memory under write-intensive loads to some extent. The lifespan of flash memory refers to the number of erasing and writing that each storage unit can withstand. When a manufacturer launches a flash memory chip, it will give the corresponding nominal life of the chip. If the number of times of erasing and writing of each storage unit is within the nominal life, the bit error rate of the flash memory is low, and the data stored on the flash memory is considered to be reliable. In fact, the flash memory can still save data in a large range after the ...

AI Technical Summary

Problems solved by technology

[0005] A comprehensive comparison of the above two error-tolerant mechanisms shows that error-correcting codes are only suitable for scenarios with low error rates. Erasure coding is suitable for scenarios with high error rates. It can correct a large number of bit errors in data with strong error tolerance, and the computational overhead is constant. However, when there are few bit errors, the computational overhead of erasure coding is higher than that of error correction. code

Using the above two mechanisms independently is difficult to extend the life of flash memory beyond the manufacturer's nominal life while ensuring IO performance

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